Implementation guide for interoperable medicines

This guidance is under active development by NHS England and content may be added or updated on a regular basis.

Element: asNeeded

Dosing 'asNeeded' and 'asNeededCodeableConcept' instructions.

Sub-element: Dosage.asNeeded[x]

The asNeeded structure can be used to define a simple “as required” (or “pro re nata” expressed as “PRN” for those who still prefer to use Latin abbreviations) instructions.

In this case use the asNeededBoolean option. The absence of asNeededBoolean is equivalent to where asNeededBoolean has a value of false.

The asNeededCodeableConcept option is used to bound the dosage instruction to a coded term. Any number of coded terms can be used from the SNOMED-CT hierarchy as a descendant of 404684003 Clinical Finding (finding). An extensive medication-as-needed-reason value-set is defined within FHIR which is a subset of the SNOMED-CT clinical findings hierarchy.

Example #1: Dosage.asNeeded

<MedicationRequest xmlns="http://hl7.org/fhir">
    <id value="c804eca2-8b32-44d7-b654-b88bb9b1edd2" />
    <meta>
        <profile value="https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest" />
    </meta>
    <status value="active" />
    <intent value="order" />
    <category>
        <coding>
            <system value="http://terminology.hl7.org/CodeSystem/medicationrequest-category" />
            <code value="community" />
            <display value="community" />
        </coding>
    </category>
    <medicationCodeableConcept>
        <coding>
            <system value="https://dmd.nhs.uk" />
            <code value="321177003" />
            <display value="Zopiclone 3.75mg tablets" />
        </coding>
    </medicationCodeableConcept>
    <subject>
        <identifier>
            <system value="https://fhir.nhs.uk/Id/nhs-number" />
            <value value="9999999999" />
        </identifier>
    </subject>
    <authoredOn value="2020-05-15T15:00:00Z" />
    <requester>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </requester>
    <recorder>
        <reference value="urn:staff-1112" />
        <display value="Dr Maikeu Well" />
    </recorder>
    <dosageInstruction>
        <text value="1 tablet - during the night - oral - as required - up to a maximum of 7.5 milligram in 24 hours" />
        <timing>
            <repeat>
                <when value="NIGHT" />
            </repeat>
        </timing>
        <asNeededBoolean value="true" />
        <route>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="26643006" />
                <display value="oral" />
            </coding>
        </route>
        <doseAndRate>
            <doseQuantity>
                <value value="1" />
                <unit value="tablet" />
                <system value="http://snomed.info/sct" />
                <code value="428673006" />
            </doseQuantity>
        </doseAndRate>
        <maxDosePerPeriod>
            <numerator>
                <value value="7.5" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </numerator>
            <denominator>
                <value value="24" />
                <unit value="hour" />
                <system value="http://unitsofmeasure.org" />
                <code value="h" />
            </denominator>
        </maxDosePerPeriod>
    </dosageInstruction>
    <substitution>
        <allowedBoolean value="false" />
    </substitution>
</MedicationRequest>

{
    "resourceType": "MedicationRequest",
    "id": "c804eca2-8b32-44d7-b654-b88bb9b1edd2",
    "meta": {
        "profile":  [
            "https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest"
        ]
    },
    "status": "active",
    "intent": "order",
    "category":  [
        {
            "coding":  [
                {
                    "system": "http://terminology.hl7.org/CodeSystem/medicationrequest-category",
                    "code": "community",
                    "display": "community"
                }
            ]
        }
    ],
    "medicationCodeableConcept": {
        "coding":  [
            {
                "system": "https://dmd.nhs.uk",
                "code": "321177003",
                "display": "Zopiclone 3.75mg tablets"
            }
        ]
    },
    "subject": {
        "identifier": {
            "system": "https://fhir.nhs.uk/Id/nhs-number",
            "value": "9999999999"
        }
    },
    "authoredOn": "2020-05-15T15:00:00Z",
    "requester": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "recorder": {
        "reference": "urn:staff-1112",
        "display": "Dr Maikeu Well"
    },
    "dosageInstruction":  [
        {
            "text": "1 tablet - during the night - oral - as required - up to a maximum of 7.5 milligram in 24 hours",
            "timing": {
                "repeat": {
                    "when":  [
                        "NIGHT"
                    ]
                }
            },
            "asNeededBoolean": true,
            "route": {
                "coding":  [
                    {
                        "system": "http://snomed.info/sct",
                        "code": "26643006",
                        "display": "oral"
                    }
                ]
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 1,
                        "unit": "tablet",
                        "system": "http://snomed.info/sct",
                        "code": "428673006"
                    }
                }
            ],
            "maxDosePerPeriod": {
                "numerator": {
                    "value": 7.5,
                    "unit": "milligram",
                    "system": "http://unitsofmeasure.org",
                    "code": "mg"
                },
                "denominator": {
                    "value": 24,
                    "unit": "hour",
                    "system": "http://unitsofmeasure.org",
                    "code": "h"
                }
            }
        }
    ],
    "substitution": {
        "allowedBoolean": false
    }
}
MedicationRequest.id[0]c804eca2-8b32-44d7-b654-b88bb9b1edd2
MedicationRequest.meta[0].profile[0]https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest
MedicationRequest.status[0]active
MedicationRequest.intent[0]order
MedicationRequest.category[0].coding[0].system[0]http://terminology.hl7.org/CodeSystem/medicationrequest-category
MedicationRequest.category[0].coding[0].code[0]community
MedicationRequest.category[0].coding[0].display[0]community
MedicationRequest.medication[0].coding[0].system[0]https://dmd.nhs.uk
MedicationRequest.medication[0].coding[0].code[0]321177003
MedicationRequest.medication[0].coding[0].display[0]Zopiclone 3.75mg tablets
MedicationRequest.subject[0].identifier[0].system[0]https://fhir.nhs.uk/Id/nhs-number
MedicationRequest.subject[0].identifier[0].value[0]9999999999
MedicationRequest.authoredOn[0]2020-05-15T15:00:00Z
MedicationRequest.requester[0].reference[0]urn:staff-1112
MedicationRequest.requester[0].display[0]Dr Maikeu Well
MedicationRequest.recorder[0].reference[0]urn:staff-1112
MedicationRequest.recorder[0].display[0]Dr Maikeu Well
MedicationRequest.dosageInstruction[0].text[0]1 tablet - during the night - oral - as required - up to a maximum of 7.5 milligram in 24 hours
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].when[0]NIGHT
MedicationRequest.dosageInstruction[0].asNeeded[0]True
MedicationRequest.dosageInstruction[0].route[0].coding[0].system[0]http://snomed.info/sct
MedicationRequest.dosageInstruction[0].route[0].coding[0].code[0]26643006
MedicationRequest.dosageInstruction[0].route[0].coding[0].display[0]oral
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].value[0]1
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].unit[0]tablet
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].system[0]http://snomed.info/sct
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].code[0]428673006
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].value[0]7.5
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].unit[0]milligram
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].system[0]http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].numerator[0].code[0]mg
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].value[0]24
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].unit[0]hour
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].system[0]http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].maxDosePerPeriod[0].denominator[0].code[0]h
MedicationRequest.substitution[0].allowed[0]False
MedicationRequest

Zopiclone 3.75mg tablets, 1 tablet, at BEDTIME, PRN, oral


Example #2: Dosage.asNeededCodeableConcept

<!--    Metoclopramide, orally 10mg to be taken when required for nausea up to three times daily    -->
<MedicationRequest xmlns="http://hl7.org/fhir">
    <id value="e02e462c-12db-4162-95f6-0436a60c5bc4" />
    <meta>
        <profile value="https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest" />
    </meta>
    <status value="active" />
    <intent value="order" />
    <category>
        <coding>
            <system value="http://terminology.hl7.org/CodeSystem/medicationrequest-category" />
            <code value="inpatient" />
            <display value="inpatient" />
        </coding>
    </category>
    <medicationCodeableConcept>
        <coding>
            <system value="https://dmd.nhs.uk" />
            <code value="56549003" />
            <display value="Metoclopramide" />
        </coding>
    </medicationCodeableConcept>
    <subject>
        <identifier>
            <system value="https://fhir.nhs.uk/Id/nhs-number" />
            <value value="9999999999" />
        </identifier>
    </subject>
    <authoredOn value="2020-05-15T15:00:00Z" />
    <requester>
        <reference value="urn:staff-3040" />
        <display value="Dr Jim Bean" />
    </requester>
    <recorder>
        <reference value="urn:staff-3040" />
        <display value="Dr Jim Beam" />
    </recorder>
    <dosageInstruction>
        <text value="10 milligram - up to 3 times a day - oral - as required for nausea" />
        <timing>
            <repeat>
                <frequencyMax value="3" />
                <period value="1" />
                <periodUnit value="d" />
            </repeat>
        </timing>
        <asNeededCodeableConcept>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="422587007" />
                <display value="nausea" />
            </coding>
        </asNeededCodeableConcept>
        <route>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="26643006" />
                <display value="oral" />
            </coding>
        </route>
        <doseAndRate>
            <doseQuantity>
                <value value="10" />
                <unit value="milligram" />
                <system value="http://unitsofmeasure.org" />
                <code value="mg" />
            </doseQuantity>
        </doseAndRate>
    </dosageInstruction>
    <substitution>
        <allowedBoolean value="false" />
    </substitution>
</MedicationRequest>

{
    "resourceType": "MedicationRequest",
    "id": "e02e462c-12db-4162-95f6-0436a60c5bc4",
    "meta": {
        "profile":  [
            "https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest"
        ]
    },
    "status": "active",
    "intent": "order",
    "category":  [
        {
            "coding":  [
                {
                    "system": "http://terminology.hl7.org/CodeSystem/medicationrequest-category",
                    "code": "inpatient",
                    "display": "inpatient"
                }
            ]
        }
    ],
    "medicationCodeableConcept": {
        "coding":  [
            {
                "system": "https://dmd.nhs.uk",
                "code": "56549003",
                "display": "Metoclopramide"
            }
        ]
    },
    "subject": {
        "identifier": {
            "system": "https://fhir.nhs.uk/Id/nhs-number",
            "value": "9999999999"
        }
    },
    "authoredOn": "2020-05-15T15:00:00Z",
    "requester": {
        "reference": "urn:staff-3040",
        "display": "Dr Jim Bean"
    },
    "recorder": {
        "reference": "urn:staff-3040",
        "display": "Dr Jim Beam"
    },
    "dosageInstruction":  [
        {
            "text": "10 milligram - up to 3 times a day - oral - as required for nausea",
            "timing": {
                "repeat": {
                    "frequencyMax": 3,
                    "period": 1,
                    "periodUnit": "d"
                }
            },
            "asNeededCodeableConcept": {
                "coding":  [
                    {
                        "system": "http://snomed.info/sct",
                        "code": "422587007",
                        "display": "nausea"
                    }
                ]
            },
            "route": {
                "coding":  [
                    {
                        "system": "http://snomed.info/sct",
                        "code": "26643006",
                        "display": "oral"
                    }
                ]
            },
            "doseAndRate":  [
                {
                    "doseQuantity": {
                        "value": 10,
                        "unit": "milligram",
                        "system": "http://unitsofmeasure.org",
                        "code": "mg"
                    }
                }
            ]
        }
    ],
    "substitution": {
        "allowedBoolean": false
    }
}
MedicationRequest.id[0]e02e462c-12db-4162-95f6-0436a60c5bc4
MedicationRequest.meta[0].profile[0]https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationRequest
MedicationRequest.status[0]active
MedicationRequest.intent[0]order
MedicationRequest.category[0].coding[0].system[0]http://terminology.hl7.org/CodeSystem/medicationrequest-category
MedicationRequest.category[0].coding[0].code[0]inpatient
MedicationRequest.category[0].coding[0].display[0]inpatient
MedicationRequest.medication[0].coding[0].system[0]https://dmd.nhs.uk
MedicationRequest.medication[0].coding[0].code[0]56549003
MedicationRequest.medication[0].coding[0].display[0]Metoclopramide
MedicationRequest.subject[0].identifier[0].system[0]https://fhir.nhs.uk/Id/nhs-number
MedicationRequest.subject[0].identifier[0].value[0]9999999999
MedicationRequest.authoredOn[0]2020-05-15T15:00:00Z
MedicationRequest.requester[0].reference[0]urn:staff-3040
MedicationRequest.requester[0].display[0]Dr Jim Bean
MedicationRequest.recorder[0].reference[0]urn:staff-3040
MedicationRequest.recorder[0].display[0]Dr Jim Beam
MedicationRequest.dosageInstruction[0].text[0]10 milligram - up to 3 times a day - oral - as required for nausea
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].frequencyMax[0]3
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].period[0]1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].periodUnit[0]d
MedicationRequest.dosageInstruction[0].asNeeded[0].coding[0].system[0]http://snomed.info/sct
MedicationRequest.dosageInstruction[0].asNeeded[0].coding[0].code[0]422587007
MedicationRequest.dosageInstruction[0].asNeeded[0].coding[0].display[0]nausea
MedicationRequest.dosageInstruction[0].route[0].coding[0].system[0]http://snomed.info/sct
MedicationRequest.dosageInstruction[0].route[0].coding[0].code[0]26643006
MedicationRequest.dosageInstruction[0].route[0].coding[0].display[0]oral
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].value[0]10
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].unit[0]milligram
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].system[0]http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].doseAndRate[0].dose[0].code[0]mg
MedicationRequest.substitution[0].allowed[0]False
MedicationRequest
Metoclopramide, orally 10mg to be taken when required for nausea up to three times daily
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